Previously, Google has said only that the algorithm - which launches on 21 April - will have a "significant impact" on search results, and would only impact mobile search.

The news is likely to come as a shock to many, considering the wide-ranging impact that the Panda and Penguin webspam algorithms had at launch. When Panda went live in February 2011, it impacted up to 12% of search queries, while Penguin's first public appearance in April 2012 saw around 3.1% of queries affected.

However, Bahajji's comments are very much open to interpretation. As Search Engine Land's Barry Schwartz asks:

Is she saying that let's say this is impacting 40% of mobile search queries, whereas Panda impacted about 12% of all English queries and Penguin was closer to 4% of global queries across both desktop and mobile. Or is she saying that across mobile and desktop, the impact will be larger than Panda or Penguin? We know the mobile-friendly algorithm only impacts mobile search results, so I'd assume she is talking about the mobile impact only.

Another interpretation is that the algorithm will have a more noticeable impact for users and brands, as rather than tackling spammy, less-than-useful sites, it will affect webpages regardless of the quality of their content or backlink profile.

Google hasn't released any estimates as to the percentage of queries that will be affected by this update. But, as Schwartz points out, it is believed that around half of Google searches are carried out on mobile devices.